With regard to vehicles in general, and at least to some extent commercial vehicles such as trucks, buses and the like in particular, vehicle economy has, over time, had an increasing impact on the profitability of the enterprise in which the vehicle is used. A main expense associated with vehicle operation is the consumption of fuel for propulsion of the vehicle.
The degree of utilization of heavy vehicles is often high, with associated considerable total fuel consumption, and the cost of fuel can affect the profitability of the owner of the vehicle to a great extent.
Fuel consumption is also of interest from an exhaust emission point of view. For example, governmental concern in pollution and air quality, e.g. in urban areas, has led to adoption of emission standards and rules in many jurisdictions. A reduction in fuel consumption facilitates fulfilment of emission standards and rules.
Any opportunity to reduce fuel consumption may affect profitability and reduction of emissions in a positive way.
For example, the use of cruise control systems is commonplace today. One common purpose of cruise control systems is to achieve a uniform predetermined velocity in a manner that is comfortable to the driver of the vehicle. However, there are also cruise control systems/functions that strive to adapt the propulsion of the vehicle based on knowledge about the road ahead, so that fuel consumption can be reduced. Such a reduction in fuel consumption can, for example, be achieved with the aid of cruise control functions where vehicle speed is allowed to deviate from a speed set by the driver based on knowledge about the vehicle route or other data, so as to thereby achieve a more fuel-economic propulsion of the vehicle.
For example, the vehicle speed may be reduced to some extent at the end of an uphill stretch that is followed by a downhill stretch of a type where, by means of the force of gravity, the vehicle will be reaccelerated to the desired speed.
WO 2013/095232 relates to a method for determination of at least one reference value which indicates how a vehicle's speed is to be influenced and which may be used to control at least one control system in a vehicle. The invention is characterized by performing the steps of:—making a first prediction and a second prediction of a vehicle speed along a horizon, said first prediction based on an engine torque which retards the vehicle as compared with a conventional cruise control, and said second prediction based on an engine torque which accelerates the vehicle as compared with a conventional cruise control;—comparing said respective first prediction and second prediction of the vehicle speed with a lower limit value and/or an upper limit value which delineate a range within which the vehicle's speed should be; and—determining at least one reference value based on at least one of said respective comparisons and said first prediction and second prediction of the vehicle speed along the horizon.